Well flow apparatus



June 23, 1953 A. l. ROBINSON WELL FLOW APPARATUS 2 Sheets-Sheet 1 Filed June 13, 1949 5. Eda/11e- A TTOR/Vf KS An I. Fob/riser? June 23, 1953 Filed June 13, 1949 2 Sheets-Sheet 2 An I. Fob/7750!? INVENTOR ATTORNEYJ Patented June 23, 1953 UNITED STATES PATENT OFFICE,

Art I. Robinson, Odessa, Tex, a's'signor toMerla Tool Corporation, Dallas, Tex., a corporation App'licati'onJune 13, 1949, Serial No. 98,863

This invention relates to new and useful improvements in a well flow apparatus.

One object of the invention is to provide an improved fiow apparatus, of the intermitting type, which is particularly adapted for use in,-although l ,noiaims. (Cl. roe-#23 3) not limited to, multiple zone wells, whereby ef-' I ficient lifting of the well fluids from the'separate producing zones may be accomplished.

An importantobject of the inventionis to provide an improved flow apparatus which employs a series of pressure-operated valves for control ling the admission of a lifting medium into a flow conductor and which hassaid valves arrangedto close when pressure of the lifting medium'is at 'a predetermined pressure with opening pressures of thevalves being controlled by' the well fluid level, whereby a fixed or constant surface pressure may be maintained in the lifting medium conductor and operation of the valves will be automatic in accordance with the well fluid conditions.

A further object is to provide 'a well flow apparatus for use in multiple zone wells wherein the lifting medium is conducted downwardly to the various Zones through a single conductor and also wherein control of the admission of the lift-'- ing medium into each well fluid conductor isindependently and automatically controlled in -a'c-' cordance with well fluid conditions in said well fluid conductor, whereby lifting of the well fluids from each zone is, in effect, independent of the production from the other zone or zones.

A particular object of the invention is to pro-- vide an improved well flow apparatus or system, of the character described, whereinfa regulated pressure may be maintained in a common lifting fluid conductor at the upp'erend of the conductor and wherein all valves are arranged to close when said regulated pressure falls to a predetermined point; the apparatus contemplating compensating for the weight of the li'fting flui'd rated between the valves which are disposed at various elevations to assure that a predetermined pressure of the lifting fluid at the surface will control the closing of all of said valves; irrespective of the elevation of said valves in the lifting fluid conductor. i "I Still another object is to provide a Well 'flow apparatus, of the character-described, for simul-" taneously lifting well fluids from a plurality of production zones wherein all valves of the ap- Y paratus are arranged to close at the same sur- 1 face pressure in the lifting fluid conductor, and wherein the pressure of the lifting fluid may be controlled either by a regulator or by the usual time-cycle controller mechanism at the surface;

, 2 'A'further object is to set ithelifting gasadmission "valves at a closing pressure which j'wi-ll be in accordance-with the elevation or position of the valve, whereby all valves-will, in efiect,'clos .e upon the attainment of a. predetermined "pressure in the lifting fluid supply conductor, with theresuit that the valves are operated to [admit lifting fluid to the well liquid conductor in accordance with well liquid conditions. 3

Still another object is to provide a well flow-- in system for lifting well liquids froma plurality of zones in the same'wel l, which-system is constructed so that the elevation or point of admission of lifting-gas into each well liquid conductor extending from each production'zone will be in accordance "with well liquid conditions in that conductor, whereby although the lifting gas is supplied froma commonsupply conductor, said gas may "be simultaneously introduced into the plurality of well liquid conductors at various elevations and in the manner required by wellliquid conditions.

Other and further objects of theinvention will appear from the description of --th e invention.

In the accompanying drawings, which form 'apart of the instant specification, which are to be 'Figu-re 2 is a transverse vertical sectional view of one of the control valves whichcontrol the admission of the lifting fluid to the inner well liquid conduotor,

Figure 3 is an enlarged horizontal cross-sectional view taken entire line 3-4] ofFi'gure 2, and

Figure 4 isa view partly insectionand partly in elevationef one "of the control valves controlling the admission of lifting fluid to the outer well liquid conductor.

In the drawings, the letter A designates a wen bore which traverses two well liquid producing zones '3 and C. "The usual well ca-sing l0 ex tends through the well bore and is formed with perforations or inlets *I I opposite the upper-producin'g'zone B whereby'the well liquids fromthis upper zone may flow upward-1y through the'well casing. The usual-casing head I2 is mounted on' the upper 'endof the-we'll casing and supports an innerjwell pipe [3 which is disposed axially within the well casing and which functions as the lifting fluid supply conductor. A tubing head I! is bolted on the casing head and supports an inner tubing string [5 which has its lower end open and communicating with the lower producing zone C, whereby the tubing may be referred to as the inner well liquid conductor. A packer l6 which may be of usual construction and which is indicated schematically packs off between the lower end of the tubing l5 and the well pipe l3 while a similar packer l1 packs off between the well pipe l3 and the well casing. By observing Figure 1, it will be apparent that the well liquids from the lower zone C may flow upwardly through the well tubing and are discharged therefrom through a discharge pipe I8 connected with the upper end of said tubing. The well liquids from the upper producing zone B enter the inlets or perforations H in the well casing and flow upwardly through said casing to be discharged through a discharge line l9 connected in the side of the casing head l2.

A lifting fluid which will be referred to herein as a lifting gas although it may be air or other fluid is adapted to be conducted into the upper end of the well pipe or supply conductor [3 through an inlet pipe which is connected within an inlet opening 2| in the side of the tubing head [4. The pressure and admission of lifting gas into the supply conductor may be controlled by the usual time cycle controller mechanism now in general use which will periodically admit a predetermined volume of gas under a desired pressure. However, with the flow valves which will be hereinafter described in detail, it is possible to simplify the surface controls and the arrangement illustrated includes a motor valve 22 which is connected in the inlet line 20. Opening and closing of the valve 22 is controlled by a regulator 23 which is actuated, through a pressure line 24, by the pressure which is present within the well pipe or conductor 13. The regulator may be any standard regulator which is available on the open marget and so long as the regulator functions to open and close the valve 22 in accordance with pressure conditions within the conductor or pipe I3 the purposes of the invention will be accomplished.

The regulator is so arranged that when the pressure in the well pipe or conductor [3 falls below a predetermined pressure the motor valve 22 is opened to admit additional pressure fluid; upon the attainment of a desired pressure within the conductor l3 which is in the annular space surrounding the well tubing [5 the valve 22 is closed to shut off the further admission of pressure fluid into said conductor. In order to control the volume of flow of pressure fluid into the well pipe or conductor [3 a suitable choke 25 is connected in the inlet line 20 and obviously this choke will limit the volume of admitted pressure fluid when the motor valve 22 is open.

A series of flow valves of the intermitter type, which are identified as Dl, D2 and D3, are con nected in the well tubing 15 at predetermined spaced levels or elevations. The construction of these valves is subject to some variation and said valves are arranged to control the admission of pressure fluid from the well pipe or conductor [3 into the well tubing I5 and when lifting gas from the pipe I3 is admitted into the well tubing said gas will function to lift the Well fluids within the tubing to the surface. The valves DI, D2, and D3 are of the intermitter type and are adapted to operate intermittently at intervals to inject a slug of lifting gas into the well liquid column.

iii)

A second series of valves identified as El, E2 and E3 are connected in the well pipe or supply conductor l3 at predetermined spaced levels or elevations therein and these valves are disposed in the annular space surrounding said pipe. The valves Ell-E3 are adapted to control the admission of pressure fluid from the interior of the well pipe I3 into the well liquid column present within the well casing and when the lifting gas is admitted to this well liquid column, said gas functions to lift the well liquids to the surface.

As will be explained, each series of valves functions to control the admission of lifting gas into one of the well liquid conductors, the valves DID3 controlling flow into the inner well tubing [5 while the valves EIE3 control the flow into the well casing. Being an intermitter type of valve the admission of lifting gas into the inner tubing l5 will be at one of the valves DID3, in accordance with the well liquid conditions in the tubing; similarly, the admission of lifting fluid into the well casing will be at one of the valves EIE3, in accordance with the well liquid conditions within the well casing. The operation is entirely automatic and the single lifting fluid supply conductor l3 functions to supply gas to both of the well liquid conductors. It might be that the operation level within the well tubing may be at the valve D2, while the operating level in the well casing may be at the valve El, which is considerably above the valve D2. Because of the manner of operation of the valve, each well 1iquid conductor operates at its best working level in accordance with the particular well liquid conditions in that conductor.

One type of intermitter valve which has been found adaptable for use in the present apparatus is illustrated in Figure 2 and as shown comprises an outer casing which is formed of an upper or pilot section 26, an intermediate or power bellows section 21 and a lower or main valve section 28. The sections 26 and 21 are connected by a coupling 29 while the sections 21 and 28 are connected by a similar coupling 30. The pilot valve section 26 includes a pilot bellows 3| which has its upper end connected to the lower portion of a closure 32 which closes the upper end of said section. The lower end of the power bellows is connected to the stem 33 of a pilot valve 34. A coil spring 35 surrounding the valve stem 33 has its lower end engaging the valve 34 with its upper end engaging an inwardly directed flange 36 which is formed at the lower end of a guide sleeve 31 within which the pilot bellows 3| is disposed.

The spring 35 constantly urges the valve into engagement with a valve seat 38, said valve seat being mounted within the upper end of the coupling 23. Inlet openings 39 are formed in the wall of the section 26 whereby the lifting gas from the well pipe or supply conductor 13 may enter the interior of the section 26 and may, through the lower end of the bore of the sleeve 31 as well as through radial ports 40 in the wall of said sleeve, act upon the pilot bellows 3 I. The pilot bellows contains a predetermined volume of liquid to protect the bellows against rupture or collapse under excessive pressure.

The pressure of the spring 35 controls the pressure at which the pilot valve 34 will open because obviously the lifting gas present within the conductor l 3 enters the interior of the section 26 and acts upon the cross-sectional area of the pilot bellows. This lifting fluid pressure must build up sufficiently to overcome the force of the spring 35 to compress the same before the pilot is opened. As soon as the pilot valve 34 opens the additional area of said pilot valve which is normally within the seat 38 is immediately exposed to the pressure and the pilot valve is moved to fully open position. As the pressure in the fluid conductor or well pipe l3 drops to a point insufficient to overcome the downward force of the spring 35 said spring overcomes the action of the pressure on the cross-sectional area of the pilot bellows 3| and the pilot valve 34 closes. It wil1 be obvious that when the pilot valve is in a closed or seated position the under side of said valve is within the axial bore 4! which extends through the valve seat and through the coupling 23 and is not exposed to the pressure of the lifting fluid within the well pipe it; when the valve is unseated this under side area is acted upon by the lifting fluid pressure in the conductor l3. Therefore, the opening pressure, that is, the pressure necessary to open the pilot valve is greater than the pressure at which the valve closes. This difference in opening and closing pressures will be referred to herein as the range or spread of the valve units DID3 and Ei--E3.

Within the intermediate section 21 is a power bellows 32 which has its lower end secured to an extension 43 formed on the coupling 38. The upper end of the power bellows is secured to an enlarged cap i i which is formed integral with an elongate operating stem 45. The lower portion of the operating stem extends through the axial bore 46 of the coupling 3! and this portion of the stem is hexagonal or angular whereby by-passages 41 (Figure 3) are formed between the stem and the bore. A radial bleed port 53 extends through the wall of the power bellows 12 so that a flow from the bore 43 to the interior of the intermediate section 2? may occur, such communication being at a controlled rate in accordance with the size of the port 48.

Thelower end of the operating stem extends into the lower main valve section 28 and is adapted to engage an axial shank 49 of a main valve member 58. The main valve member is arranged to seat upon an annular valve seat 5i when in its upper or raised position.

In the case of the valves Di-D3, a radial port 52 extends from the bore Zea ot the section 28 and communicates with an inlet port 53 formed in the well tubing l5 and thus communication is established between the bore of the lower section D and the interior of the well tubing. Inlet 54 is provided in the lower end of the lower section 28 and when the main valve is open a flow from the well pipe or supply conductor 53 past the valve and through the inlet ports 52 and 53 into the inner well tubing i 5 may occur. -Because the valves EiEl3 are mounted exteriorly ofthe supply conductor or well pipe I3 these valves must be slightly modified as illustrated in Figure 4. The internalconstruction of the valves El-E3 is identical to the structure of the valves Dl-D3, "the only difference'being in the connections wherebythe gas from the conductor i3 is directed through the valves. As illus trated in Figure 4, only a single inlet 39a is provided in the pilot bellows section 26 of the series E valves and this inlet is connected through a nipple connector 55 with a port 55 provided in the wall of the well pipe or conductorl3. In this manner the lifting fluid may constantly enter the upper section 26 to act upon the pilot bellows 3| just as in the case of the D series valves. Each o f'the valves Eli-E3 has an elbow 51 connected bleed port 48 in the belloi s into the bore 21a of 6, to the lower end of the lower section 28,, this elbow being substituted for the inlet 54 of the D series valve. The elbow communicates through an inlet port 58 with the interior of the conductor or pipe l3. It will be evident that the valves El-E3 will function in an identical manner to the valves DID3 since the lifting fluid pressure is constantly acting against the pilot bellows 31. When this pressure overcomes the pressure of the spring holding the pilot valve closed the pilot valve is opened todirect the lifting fluid pressure against the upper end of thepower bellows 52; Since the power bellows has a larger cross-sectional area than the area of the main valve which is also acted upon bythelifting fluid pressure the main I valve is lifted downwardly off of its seat to allow the lifting fluid pressure to flow through the inlet 52 in the lower valve section 28. In the case of the valves EliEi, the lifting fluid flows through the port 52a directly into the well casing, whereas in the valves Dl-DB the lifting fluid flows through the inlet 52 then through port 53 into the inner well tubing 15.

Since all of the valves are of identical construction and operate in a similar manner, it is believed that a description of one will suflice. Referringto Figure 2 which illustrates the valve Di, it will be evident that with a pressure within the well pipe 23 such pressure will act against the lower end of the main valve 5i! to maintain the same seated. This pressure will also act through the ports 39 in the piiot'section 25 and upon the pilot bellows, but presuming that such pressure is insuflicient to open the pilot valve the main valve 50 remains closed. Any back pressure on the valve, thati's, any pressure from within the inner well tubing $5 in the case of the series D valves or any-pressure within the well casing It in the case of the series E'valves, will act through the port 53 and within the bore 28a of the lower section 28. This back pressure flows upwardly past the angular portion or the operating stern and into the interior of the power bellows and then through the the intermediate section 21'; -he bore 21a of the intermediate section is in communication with the bore 4| of the coupling and thus the back valve and under such a condition the pilot valve will remain closed until the pressure within the well pipe I3 is suflicient to overcome the tension or force of the coil spring 35. I

For the purposes of this description and merely by way of' example, it will be presumed that under atmospheric conditions the closing pressure of the pilot valve 34 is 400 pounds while. opening pressure will be presumed to be 460 pounds. Under this assumption, when the pressure in the well pipe i3 reaches 460 pounds the pilot valve opens and the pressure of the lifting fluid within the pipe i3 acts on the exterior :of the power bellows 42 and functions to compress or collapse saidbellows to move the'operating stem downwardly and thereby open the main valve 50. Openingof the main valve allows a flow of pressure fluid into the well tubing l5 when the -D series valve operates or into the well casing when the E series valve operates; Just as soon, as the pressure within the well pipe [3 falls below the assumed closing pressure of 400 pounds the pilot valve 34 is closed by the spring 35. The pressure exteriorly of the power bellows is bled off through the bleed port 48 thereby permitting the differential across the main valve 50 to move said valve to its closed position.

It will be evident that any back pressure present within the well liquid conductor will act against that cross-sectional area of the pilot valve 34 which is exposed within the valve seat 38 and this back pressure will be added to the lifting fluid pressure which is tending to open the pilot valve. Therefore, with a back pressure present within the well liquid conductor the opening pressure of the valve is altered and, as a specific example, it has been found that with a presumed opening pressure of 460 pounds at atmosphere, a back pressure of 100 pounds acting on the pilot will cause the valve to open when the pressure within the supply conductor I3 reaches 445 pounds. A back pressure of 200 pounds acting against the pilot will reduce the opening pressure to 432 pounds, while a back pressure of 300 pounds will further reduce the opening pressure to 420 pounds. This reduction in the opening pressure is, of course, based on the particular ratio between the area of the pilot valve seat 38 with respect to the effective crosssectional area of the pilot bellows, for obviously b varying the ratio between the area of the 7 sure; however, in all cases with the valves con- 1 structed identically, the closing pressures will remain the same which as presumed will be 400 pounds. Therefore, actually the operating range or spread of the valve, that is, the spread between opening and closing pressures, varies proportionately to the back pressure acting on the valve. The particular operating range or spread may, as above pointed out, be controlled accurately by varying the ratio between the diameter of the valve seat and the effective cross-sectional area of the pilot bellows.

As above pointed out the spring 35 controls the closing pressure and as will appear in the operation of the apparatus, it is desirable that the closing pressure of all of the valves in the apparatus be exactly the same. If all of the valve springs 35 were of exactly the same strength then the closing pressure under atmospheric conditions would be identical in all valves. However, it is obvious that the valves are disposed at different levels or elevations within the well bore and the volume of gas between valves has a certain weight. This weight of gas which is, of course, in proportion to the spacing between valves is added to the pressure of the lifting gas which is present within the pilot section 26 and thus, the valves which are disposed lower in the system will be actually subjected to a greater pressure than will the valves in the upper part of the system. It is, therefore, necessary to compensate for the weight of the gas which is present between valves in the system and this is done by varying the pressure of the spring 35 in direct proportion to the weight. Thus, if the valves are spaced 100 feet apart in the installation the weight of the gas above each valve is taken into consideration in setting its closing pressure. By compensating for the weight of the gas between the valve units all of said valves will close when the pressure within the pipe I3 falls to a predetermined point. In other words, when the pressure in the pipe or supply conductor I3 drops to 400 pounds all of the valves in the system will close. Each valve may not have a test block closing pressure of 400 pounds but its test block closing pressure taken with the weight of the gas thereabove makes the valve close when the actual lifting gas pressure drops to 400 pounds. The compensation for the weight of the gas is an important feature of the present invention since it assures that all valves will close when the pressure in the pipe or conductor I3 reaches a predetermined point.

In the operation of the apparatus all of the valves DI-D3 and EIE3 will be assumed to have a presumed closing pressure which will cause said Valves to close when the pressure within the well pipe or lifting fluid supply conductor I3 drops to 400 pounds. All of said valves may be constructed with their pilot bellows bearing the same ratio to their pilot valve seat. Under such a situation the operating range between opening and closing pressures on all valves would be alike with the same back pressure condition. However, if desired, certain of the valves may have different ratios between the pilot valve seat and the pilot bellows in which event the operating range or spread between opening and closing pressures oi such valve under a given back pressure condition would be different from the remaining valves. At the start of the operation, fluid will be present within the well casing and will also be present within the inner well tubing so that all of the valves will have some back pressure thereon. Considering first the lifting operation which is carried out within the inner well liquid conductor formed by the tubing I5 the lifting fluid is admitted into the well pipe I! through the supply pipe 20. As the pressure is built up in the well pipe to a point suflicient to open the uppermost valve DI, a charge of gas is admitted into the flow tubing and the liquid above this level is lifted to the surface so that the back pressure on this particular valve becomes substantially nil. At the time that sumcient pressure has been built up to open the upper valve all of the lower valves having a greater back pressure will, of course, be open and may be in a position with the main valve 50 lowered against a back check seat 54a to prevent reverse fiow of well liquid from the tubing back into the well pipe.

Referring back to the uppermost valve DI, under the presumed conditions the opening pressure at atmosphere of this valve is 460 pounds while under a pound back pressure the opening is 445 pounds. Therefore, assuming a 100 pound back pressure against valve DI at the start of the operation when the pressure within pipe l3 reaches 445 pounds, the valve opens to admit lifting fluid to the tubing and thereby unload the tubing above said valve. This unloading eliminates the back pressure acting on valve DI and immediately the opening pressure of this valve is raised to 460 pounds. Thus, the upper valve becomes inactive after it has initially opened to admit fluid and since the next valve therebelow has some back pressure on it its opening pressure is less than the pressure of the uppermost valve. The valves are operated successively in this manner to unload the liquid in the tubing and until the working level is reached, such working level being at the point where the flow-- ing bottom hole pressure of the well feeds past the valve at a pressure equal to or slightly less than the operating pressure of that valve. In other words, this level may be found at valve D2 or it may be at valve D3. After the well tubing is unloaded subsequent admission of lifting fluid is only through the valve at the working level and all of the valves thereabove remain inactive until such time as the back pressure conditions within the tubing change so as to bring these valves in operation. The valve at the working level will remain open until sufficient lifting fluid has passed into the well tubing to reduce the pressure in the pipe I3 to the assumed 400 pounds closing pressure of the valve. In other words, when the pressure in the pipe l3 drops to 400 pounds the valve will close and will remain closed. Assoon as the pressure in the casing I3 drops to a point close to the 400 pound closing pressure, as for example, at 405 pounds,

the regulator 23 will function to open the motor valve 22 and admit additional lifting fluid into the pipe I 3. The choke 25 is so arranged that its capacity is less than the capacity through the valves, with the result that the lifting gas is admitted into the pipe in a volume less than that passing through the valve. Therefore, even though pressure fluid is being admitted into the pipe l3 during the time that the valve is open, it is not admitted in suflicient volume to prevent a further reduction .inthe pipe 13 to the 400 pound pressure which effects closing of the valve.

As soon as the closing pressure is reached in the pipe l3 the valve at the working level closes but the regulator continues to hold the inlet valve 22' open until the pressure in pipe [3 has again built up to the pressure which will be required to open the valve when the fluid column has built up to the required back pressure.

If the working level is at the valve D2 and assuming that the valve D2 is operated on a 32 pound spread, the valve would reopen when the pressure within the pipe l3 reaches 432 pounds with a 200 pound back pressure exerted by the liquid within the tubing. In other words, valve D2 will close when the pressure within the pipe drops to 400 pounds and will open when the pressure in the pipe is 432 pounds with the liquid level in the tubing exerting a 200 pound back The regulator will function to shut pressure. off the pressure at 432 pounds which will be maintained in the pipe and thus the valve DI will not reopen for the next gas admitting cycle until the well liquids have built up in the tubing to a point sufficient to exert 200 poundsback pressure on the valve.

The bleed port 48 which is provided for bleeding the interior of the power bellows enters into the operation of the device in that it controls the amount of pressure which is obtainable in the power bellows during operation. By'changing the size of this bleed port" with respect to the size of the pilot seat bore it is possible to control or vary the amount of pressure which may be obtained in the power bellows. Thus, it will be seen that the ratio between the pilot seat and the effective cross-sectional area in the power bellows is the governing factor in controlling the operating range or spread which is had under certain pressure conditions. The ratio between the pilot seat and the power bellows bleed port 48 enters into efficient valve operation, that is,

level in the well casing. Thus, the valve D2 may be operating to admit lifting fluid at the proper times to the well tubing while the valve E2 which is at a considerable higher elevation may at the same time be functioning to admit lifting fluid to the well casing. Assuming the working levels in the two liquid conductors to be at the valves D2 and E2 and also assuming that the valve D2 operates first, it will be evident that the admission of lifting fluid into the well tubing will result in a lowering of the pressure in the well pipe [3 which pressure will drop belowthe pressure at which all valves close. Thus, the uppetr valve'E2 cannot open during the time that the pressure in the well pipe is below 400' pounds which is the assumed pressure at which all valves close. Upon the lifting operation being com pleted through valve D2, valve D2 closes and immediately the regulator functions to build the pressure back up in the gas supply pipe l3. to the predetermined substantially constant pressure. As soon as this pressure is built back up and as soon as a sufficient back pressure is exerted through the casing on valve E2 this valve will open to raise the liquid in the well casing. Opening of the valve E2 reduces the pressure in pipe I3 down to 400 pounds which is the assumed pressure at which all valves close and. at this point the valve D2 cannot be actuated. Thus, even though the liquid level within the second liquid conductor has builtup a back pressure which would ordinarilyopen the valve, said valve will not open during the flowing of the other liquid conductor because of the pressure drop in the pipe 13. However, immediately upon the pressure in pipe [3" being raised the other valve can immediately'operate. 7

From the foregoing it willbe seen that an improved apparatus for lifting well liquids through two liquid conductors from a single supply source of lifting gasis provided. Each series of valves associated with a liquid conductor operates independently of the other series although both are supplied with lifting gas from the single source. An important feature of the invention is the initial setting of all valves to compensate for the weight of the gas which would create a difference due to different elevations or locations of the valves and the apparatus is such that when the pressure in the lifting gas sup-ply conductor or pipe I3 falls to a predetermined point all valves are closed at that pressure. The regulator and chokeare important in the operation of the system because the choke controls the volume of incoming pressure fluid during the operation of the valve which is functioning at the working level, whereby the pressure in the pipe I3 may fall to the predetermined point at which the valve will close before the pressure is again built up within said pipe. The use of a regulator and choke provides for a simplified arrangement but it is evident that a time cycle a controller such as is now in general use with flow valve intermitters could be employed. When a time cycle controller is employed, it will control the admission of lifting gas to the supply conductor at predetermined intervals and obviously the valves DID3 and E|E3 will function in the same manner as heretofore described.

It is also pointed out that although the arrangement has been shown as applied to dual production the feature of compensating for gas weight between the valves could be employed in a single production string so that the various valves in the string would all close when the pressure in the lifting gas supply conductor falls to a predetermined point. Therefore, the invention is not to be limited to dual production, although it is readily adaptable for such use.

From the foregoing it will be seen that this invention is one wall adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having described the invention, I claim:

1. A well flow apparatus for lifting well liquids from a plurality of producing zones in a single well bore including, a well liquid conductor extending from each producing zone, a lifting fluid supply conductor extending within the well bore and common to all well liquid conductors, a plurality of series of pressure-actuated valves adapted to control the admission of lifting fluid to the well liquid conductors, each series of valves being associated with one of th well liquid conductors and being disposed at spaced elevations along said well liquid conductor, means for maintaining a predetermined constant lifting fluid pressure in the supply conductor, means in each valve actuated by the back pressure developed by the well liquid in each well liquid conductor for opening one of the valves in each series of valves to admit lifting fluid to the well liquid conductor associated with that series of valves, and means for adjusting the closing pressure of each valve to compensate for the weight of the lifting fluid thereabove, whereby all of the valves have the same effective closing pressure and all of said valves are thereby closed when the pressure in the supply conductor falls to a predetermined point.

2. A well flow apparatus as set forth in claim 1, wherein the means for supplying additional lifting fluid to the supply conductor is operated when the pressure falls to a predetermined point.

3. A well flow apparatus as set forth in claim 1, wherein the means for supplying additional lifting fluid to the supply conductor is operated when the pressure falls to a point just above the point at which said valves will close, and means for controlling the admission of the additional lifting fluid into the supply conductor to admit it at a volume less than the volume flowing through the open valves whereby said supply conductor pressure may fall to the closing pressure of said valves before being again built up to the desired point.

4. A well flow apparatus including, a vertical well liquid conductor for conducting well liquids from a sub-surfac producing formation, a lifting fluid supply conductor extending parallel to said Well liquid conductor, a plurality of communicating passages establishing communication between the lifting fluid supply conductor and the Well liquid conductor and disposed at spaced elevations along the well liquid conductor, a pressure-actuated valve in each passage for controlling flow therethrough, each valve having a closing pressure which will close the valve when a predetermined pressure is present in the supply conductor and no back pressure is present in the well liquid conductor, a predetermined selected increase in the back pressure within the well liquid conductor due to a rise in well liquids resulting in opening of one or more of said valves subjected to th predetermined back pressure to admit lifting fluid to said conductor, means in each valve for initially setting the valve to a closing pressur which takes into consideration the Weight of the column of lifting fluid above the valve to compensate for the difference in position or elevation of the valve, whereby reduction of the pressure in the supply conductor to a predetermined point will result in a closure of all of said valves irrespective of their elevation within the supply conductor.

5. A well flow system including, a flow conductor, a series of pressure-actuated valves connected with the conductor at various elevations therein for controlling admissions of a pressure fluid into said conductor, each valve being set to operate at progressively higher pressure range than the valve next above, whereby the highest pressure range valve is at the lowest elevation in the conductor, and means to introduce a pressure fluid into the well as a charge to open such valve or valves as will open by the fluid pressure occurring in the well due to the introduction of said charge.

6. A well flow system including a flow conductor, a series of pressure-actuated valves connected with the conductor at various elevations therein for controlling the introduction of a lifting fluid from the area exteriorly of the conductor into said conductor, each valve being set to operate at a progressively higher pressure range than the valve next above, whereby the highest pressure range valve is at the lowest elevation in the conductor, means for maintaining the pressure fluid exteriorly of the conductor at a substantially constant pressure, means in each valve controlling the operating range, and the operating range of each valve being determined in accordance with the pressure of the lifting fluid plus the weight of the column of lifting fluid above said valve.

'7. A well flow system including a flow conductor, a series of pressure-actuated valves connected with the conductor at various elevations therein for controlling the introduction of a lifting fluid from the area exteriorly of the conductor into said conductor, means for maintaining a pressure fluid exteriorly of the conductor at a substantially constant pressure, means Within each valve for setting the effective closing pressure thereof, whereby all of said valves have the identical effective closing pressure, said closing pressure for each valve being determined by the pressure of the lifting fluid added to the pressure exerted on the valve by the weight of the column of lifting fluid above said valve.

8. A well flow system including, a well casing extending within a well bore and having communication with a sub-surface well liquid producing zone, an inner well pipe forming a lifting fluid supply conductor extending axially within the casin a well tubing disposed axially within the pipe and having communication with a second sub-surface producing zone, a series of pressure-actuated valves disposed at various elevations along the well pipe for controlling the admission of lifting fluid into the well casing, a second series of valves disposed at various elevations along the Well tubing for controlling the admission of lifting gas from the well pipe to the well tubing, means for maintaining the lifting fluid at substantially a, constant pressure in the well pipe, means within each valve for initially setting each valve of both series of valves to a closing pressure which is determined in accordance with the pressure of the lifting fluid and the weight of the column of lifting fluid above that valve whereby the differences in the elevations or positions of the valves are compensated for and all valves have the same effective closing pressure.

9. A well flow system as set forth in claim 8, wherein the means for maintaining the pressure in the well pipe is a regulator, and a choke mounted in the inlet to the Well pipe for restricting the volume of lifting fluid admitted tosaid pipe.

10. A well flow apparatus including, avertical the lifting fluid supply conductor and the well.

means of each valve being adjusted to compensate for the weight of the lifting fluid in the supply conductor thereabove whereby the effective closing pressure of all valves is the same to effect closing of all of said valves when a predetermined pressure is present in the upper end of the supply conductor and no back pressure is present in the well liquid conductor.

11. A well now apparatus as set forth in claim 4, together with a time cycle controller at the I surface of the lifting fluid supply conductor for well liquid conductor for conducting well liquids from a sub-surface producing formation, a lifting fluid supply conductor extending parallel to said well liquid conductor, a plurality of communicating passages establishing communication between Deriodically admitting lifting fluid under a predetermined pressure into said conductor.

- ART I. ROBINSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,008,172 Bryant 'July 16, 1935 2,204,834 Temple r. June 18, 1940 2,298,834 Moore Oct. 13, 1942 2,339,487 King Jan. 18, 1944 2,342,301 Peters Feb. 22, 1944 

